Recently, a solar cell that does not generate CO2 for a power generation has been spread because of concern over global warming. However, the power generation using the solar cell has a problem that a power generation amount varies depending upon a period of time, and depending upon even a season. In order to solve this problem, there has been considered a power generation system that stores power, which is generated through the power generation by the solar cell, as hydrogen generated from an electrolysis of water, and eliminates the variation in the power generation amount by the power generation of a fuel cell employing the hydrogen gas as a fuel. Therefore, various techniques combining a solar cell and an electrolytic cell have been proposed.
For example, Patent document 1 describes a hydrogen production device that has a thin-film solar cell and an electrolytic catalyst layer, which are formed in parallel on a transparent electrode film formed on a substrate, and that can electrolyze an electrolytic solution by irradiating light to the thin-film solar cell.
Patent document 2 describes an electrolytic system that outputs an optimized electromotive force of a solar cell to an electrolytic cell so as to generate hydrogen gas and oxygen gas.